Project III uses a longitudinal research design to analyze Mexican children of immigrants'access to and use of health care. The project will evaluate how immigrant documentation status creates health care access vulnerabilities and how institutional and sociopolitical contexts in new and traditional immigrant destination communities may reduce health care barriers. While nearly one-third (29%) of Mexican children lack health insurance and an estimated 16% do not get regular medical checkups, little is known about the effects on health care access and use of the immigration and settlement process or the legal status of parents and children. This study will address these research gaps using pooled longitudinal data from four nationally representative cohorts from the 1996, 2001, 2004 and 2008 panels ofthe SIPP merged with contextual data on public and school-based health facilities, economic conditions, and largely restrictive local area immigration-related laws and policies. Rates and types of insurance coverage, gaps in coverage over time (e.g., by year), and receipt of routine medical and dental care will be examined by race-ethnicity, nativity, and legal status, and across new versus traditional immigrant destination contexts. The proposed analysis will advance public health scholarship regarding multiple dimensions of new and traditional destination contexts that are related to health care access and utilization (i.e., health- and work-related institutional contexts, the immigrant receptivity context). Methodological innovations address several challenges inherent in the study of immigrant populations, including the development and validation of an algorithm to estimate immigrant documentation status;development of propensity scores for use in sensitivity tests for bias in model estimates due to selection into new/traditional destination communities and for use in creating emigration adjusted weights;and the multi-source measurement of immigrant receptivity "climate," including local area enacted immigration-related laws and policies and media-documented records of immigration-related community social actions.